1. Field of the Invention
This invention is directed to the substantial reduction of nitrogen compounds, such as NO and NO.sub.2, and particulate emissions from combustion engines by the addition to the engine's fuel of an organosulfur-containing transition metal complex, e.g., nickel thiobis(4-t-octylphenol-phenolate). This invention is accordingly further directed to the novel use of these organosulfur-containing complexes as additives for reducing hydrocarbon base fuel emissions.
2. Description of the Prior Art
Energy-absorbing complexes and chelates of nickel are known for the stabilization of polymers against the effects of light.
Heskins and Guillet (1) first proposed the energy transfer mechanism of UV protection in 1968.
Commercially available UV stabilizers are listed by class and function, and identified as to structure, in the Kirk-Othmer Encyclopedia, 08 Chemical Technology, 2 Edition, Vol. 21, pages 115-122.
Uri(2) cites conventional antioxidant effects (hydroperoxide decomposition and free radical capture) of bis(stilbene-dithiolato)nickel. ##STR1## as well as its UV inhibiting properties. These functions, however, are discussed in terms of polymer and pure hydrocarbon substrates. Uri also summarizes the photo chemistry of excited species in polymer degradation.
Coping and Uri are authors of a British Patent Specification (3) which claims bis(stilbenedithiolato)nickel as antioxidant for organic materials including polymers and hydrocarbons.
It appears that no work in fuels, e.g., hydrocarbon fuels relative to energy transfer mechanisms and nickel organosulfur-containing complexes and chelates has been reported.
Concern for the environment is leading to more stringent requirements on engine emissions. Use of the energy-transfer additive concept, to minimize the reaction sequences which normally lead to NO.sub.x and/or particulate emissions, as an emission control route is therefore of major significance in fuel technology, particularly for diesel engines.